Friday, March 20, 2009

Six Sigma is a quality management program that is designed to achieve a “six sigma” level of quality for products. In the mid 1980s, Motorola pioneered Six Sigma and it has since been adopted by many other companies and manufacturers. Service companies also implement Six Sigma strategies to improve customer service and relations. The idea behind Six Sigma is that failures in quality and customer satisfaction occur after the sixth sigma of likelihood in a normal distribution curve. Hence, the idea is that there are less defects per product or customer service. Motorola defines the success of six-sigma quality in terms of the number of Defects Per Million Opportunities.

Why Use Six Sigma?

Many companies and critics of Six Sigma believed that achieving six levels of quality was impossible, but many companies have proved the critics wrong. Some companies even go beyond six-sigma. An example of this is GE Aircraft Engines, which operate at Nine Sigma levels of quality. Six sigma is practical because it reduces the amount of errors in customer service and products. This leads to increased customer satisfaction, increased revenue, more returning customers, and the acquisition of new customers. Companies that can implement six-sigma successfully have higher standards of quality and usually produce better products and services.

Why is it only Six Sigma?

Many people do not know how six-sigma relates to 3.4 defects per million. Essentially, people do not know how having six levels of sigma improves quality significantly. Many companies used to have less sigma, usually about three or four. However, Motorola was the first to use six levels. Six is the perfect number because whereas four sigma makes sure that there are only about 2.6 problems in a thousand. However, the problem arises with deviation. Imagine a manufacturing process in which a drill makes a hole that is supposed to be 100 micrometers. With four levels of Sigma, only about 1 in 400 will be defective. This unfortunately does not take into account the average value of measurement, which will shift over time. So, if the measurement gradually drifts as each new hole is drilled, about 6.6% of the output will be off by 1.5 sigma in each direction at anytime. If the process has drifted by 150 micrometers, then the hole will be off by 300 micrometers, which is an extremely large defective rate. Using 6 sigma, with a 1.5 sigma shift to make up for average deviation, the ratios are much lower and therefore the defective rates are much more sensible. The same drift in a six-sigma process will still only produce a defect for products or services that are more than 4.5 sigma away from the average in the same direction. Using the mathematics of a normal curve, this works out to 3.4 defects per million which is much more acceptable.

Conclusion

Customers value quality above all other things in a business. If a business produces a high quality product or service, more customers will return, and that business will gain new customers. Six-sigma helps to ensure the quality of goods and services is only the best. Six-sigma, when implemented correctly, is very effective and that is why many companies today use Six-sigma. This process was pioneered more than 20 years ago by Motorola, and has proven its lasting qualities through its continued use in the business world. Any company that wants to gain and retain customers while producing a high-quality product should consider the use of Six-sigma.